This invention relates to apparatus for use in cutting material. More particularly this invention relates to a ultrasonically vibrated cutting apparatus suitable for cutting fibers or threads. Such apparatus is useful as a thread cutting mechanism in conjunction with industrial sewing machines. During such applications, a thread cutter functions to sever the needle thread and the bobbin thread when stitching in a fabric is completed or to sever the "thread chain" during overstitching. The former application is generally referred to as a thread trimmer, or more appropriately as an under-bed thread trimmer where the mechanism is located below the sewing machine plate supporting the fabric. The latter application is referred to as an overedge chain cutter. At present conventional under-bed thread trimmers are of two types. In one type a high velocity knife edge cuts threads upon contact. A second type operates in a shearing manner similar to scissors. For either type, the needle and bobbin threads are displaced from normal to cutting position by a "picker" so as to insure that sufficient lengths of thread remain at the needle and bobbin. Among the disadvantages of such high-velocity knife thread cutters is their relative mechanical complexity. Such complexities, besides being expensive, lead to maintenance and adjustment problems particularly the latter where the thread characteristics change.
Similarly, a shearing cutter employing either rotary, rectilinear or pivotal motion between two cutting edges is usually a rather complex apparatus (device) and as a result lacks desirable reliability and results in excessive maintenance. For instance, adjustments and maintenance of edge sharpness is critical in such devices.